Although the commercial market of tile roofing is quite crowded, and a competitive one, it is yet very conservative in terms of costs per square meter, that is nearly the same all around the globe. It seems that during several decades of years, or even more, there have been achieved a stable balance between the requirements in which a roofing element should withstand (i.e. minimal load to be carried by, its stability to wind and so on) and between the minimal quantity of raw material that should be used in order to comply with the requirements. When referring to sheet metal tiles, for example, the costs per square meter are mainly derived from the price of steel in the international market, that is substantially fixed.
It is therefore a very high motivation for the competitor manufacturers in such market to affect a reduction, let say even of a few fractions of a percent, in their expenses per square meter roofing.
On the background of said conservative market, the object of the present invention is to provide the knowledge how roofing costs may be reduced in tens of percents.
It should be considered that although the discussion from now on in this specification will hang around steel made roof tile, the present invention does not limit itself to this specific material. The same principles that will become more apparent after reading the technical parts of this text, apply for a variety of manufacturing materials without departing from the scope of this invention.
More than twenty years ago, the invention disclosed by the WO 81/03196 publication (hereinafter will be referred to as “D1”) was aimed and directed to show how the purlins that used to be an integral part of the traditional infrastructural construction of tile roofs, are replaced by purlins that are integral part of the roofing tile itself, while the roofing infrastructural construction is comprised of rafters only, i.e. without purlins.
The integral purlin according to said invention is made in the tile by a modification in its shape and with no significant increase in the amount of material that should be used. The actual implementation of said patent could be found in a product named “Scanroof”, which is manufactured by the assignee of the invention disclosed by said D1 publication.
The benefit in using this D1 invention is double: firstly there is a reduction in the amount of material that should be used for the infrastructural construction since purlins are no more necessary, and secondly there is a reduction in the working time that should be spent to erect the economical construction.
U.S. Pat. No. D288,771 publication (hereinafter will be referred to as “D2”) discloses a support strip which as could be appreciated is aimed not only for supporting but also to help in positioning and assembling of the D1 type tile, that is necessary since the tile itself does not contain means that ensures precise positioning and assembling of one roofing sheet respect to another, and as will be explained in detail in the following chapters of this specification.
As mentioned before, the motivation of a manufacturer to reduce production costs is clear, hence, it is believed whether there was a chance to utilize the technical features disclosed by said inventions by those who skill in the art in order to reduce roofing production costs furthermore, it was completely exhausted, either by the assignees of the patents that were granted to said invention in several countries, or by manufacturers in other countries, were the invention was not protected. More than three years after the expiry of the patent term, and despite of a long felt need, no body in the market of steel tile roofing shows ability to break through the bar and to reduce the roofing manufacturing costs beyond the effective limits determined by said invention.
It is therefore an object of the present invention to provide a new set of features that will allow for a reduction of up to several tens of percents in the manufacturing costs of steel tile roofing.